1) Field of the Invention
The present invention relates to adhesive tapes for electronic parts to be used for adhering between parts around leadframes making up a semiconductor device, e.g., lead pins, semiconductor chip mounted substrates, heat spreader, semiconductors themselves.
2) Description of the Related Art
Conventionally, adhesive tapes for fixing a leadframe, TAB tapes, etc., are used as adhesive tapes for use in the interior of resin-molded type semiconductor devices. For example, the adhesive tapes for fixing a leadframe have been used to fix lead pins of the leadframe in order to enhance the efficiency for producing the leadframe itself and the whole semiconductor assembly stages. In general, a leadframe manufacturer tapes a leadframe, and brings it to a semiconductor manufacturer, at which a semiconductor chip is mounted thereon followed by molding the leadframe with a resin. For this reason, it has been required for the adhesive tapes for fixing the leadframe not only to possess general reliability in a level required for semiconductor and enough processability at the time of taping, but also to possess sufficient adhesive strength at room temperature immediately after taping and heat resistance enough for withstanding thermal process at the stages of assembling semiconductor devices.
Conventionally, the adhesive tapes for use in such an application include adhesive tapes applying on a support film of a polyimide film, etc., an adhesive comprising polyacrylonitrile, polyacrylate or a synthetic rubber resin such as acrylonitrile-butadiene copolymer solely, or modified with any other resin or blended with any other resin to come into a B-stage.
In recent years, resin-molded type semiconductor devices as shown in FIGS. 1 to 3 have been developed or produced. In FIG. 1, the device has a construction in which lead pins 3 and plane 2 are connected by means of an adhesive layer 6, a semiconductor chip 1 is mounted on the plane 2, and together with bonding wires 4 between the semiconductor chip 1 and the lead pins 3, they are molded with a resin 5. In FIG. 2, the device has a construction in which the lead pins 3 on the leadframe are fixed with the semiconductor chip 1 and an adhesive layer 6 and together with a bonding wire 4, they are molded with a resin 5. In FIG. 3, the device has a construction in which a semiconductor chip 1 is mounted on a die pad 7, electrode 8 is fixed with an adhesive layer 6, the spaces between semiconductor chip 1 and an electrode 8 and between the electrode 8 and lead pins 3 are each connected with bonding wires 4, and they are molded with a resin 5.
In the adhesive layer in the resin-molded type semiconductor devices shown in FIGS. 1 to 3, the use of an adhesive tape to which a conventional adhesive is applied has the problems that the generated gas stains the lead to cause deterioration of the adhesive strength or causes generation of package crack, because of insufficient heat resistance.
The present invention has been made in the light of such situations associated with the prior arts and in order to improve such situations. An object of the present invention is, therefore, to provide an adhesive tape and a liquid adhesive for electronic parts having sufficient heat resistance and reliability.